
\(\mathbb {E}\colon \mathcal {C}^{\rm op}\times \mathcal {C}\rightarrow \rm {Ab}\)  is an additive bifunctor;

\(\mathfrak {s}\)  is an additive realization of \(\mathbb {E}\) ; and

\(\mathbb {E}\)  and \(\mathfrak {s}\)  satisfy certain axioms in [1]}.

